Use gender neutral pronouns
Something that had been bothering me lately is the fact that Gajim uses "his or her" or "his (her)" instead of the proper English gender neutral pronoun, "their".
On top of inclusivity issues, it results in text consistency issues and just makes the text more complicated to understand.
I can send a PR for this, I have committed the changes required to my fork here, though I can't figure out how to build the translations (and I think that my fork breaks some msgids). If needed, I can edit all the translation files manually. Perhaps I should turn this into a PR with WIP.